GENERATION AND VALIDATION OF OXYGENATED VOLATILE ORGANIC-CARBON STANDARDS FOR THE 1995 SOUTHERN OXIDANTS STUDY NASHVILLE INTENSIVE

Two volatile organic compound (VOC) mixtures were made available and u tilized for the calibration of instruments and intercomparison exercis es at the Youth, Inc. (YI) site during the Southern Oxidants Study Nas hville Intensive. Cylinder I, made by Scott-Marrin, Inc., contained 14 components (3 nonmethane hydrocarbons (NMHCs) and 11 oxygen-containin g VOCs (OVOCs)) and is referred to as OVOC1. Cylinder 2, made at the N ational Center for Atmospheric Research (NCAR), contained 4 components (one NMHC and three OVOCs) and is referred to as OVOC2. The mixtures were not prepared by either laboratory as primary standards but signif icant effort was applied to validate their concentrations by several d ifferent laboratories using several different techniques. The mixtures were prepared in high-pressure cylinders in the parts per million by volume (ppmv) range using calibrated syringe methods. Gas chromatograp hic (GC) and 2,4-dinitrophenylhydrazine (DNPH) cartridge/high-pressure liquid chromatographic (HPLC) systems were utilized in the calibratio n of the cylinders. GC detectors included the flame ionization detecto r (FID) and atomic emission detector (AED). Results obtained with the GC/FID systems for OVOCs were adjusted in terms of the effective carbo n number (ECN), obtained from literature values, to correct for the re duced response of the FID for compounds containing oxygen, relative to compounds containing only carbon and hydrogen. Cylinder concentration s were derived and compared based on the ECN-adjusted FID results, the AED results, and the DNPH cartridge results. The various methods empl oyed agreed to within approximately 15%. Both cylinders were stable (/-4%) over a period of 2 years.